A heat pump system and a defrosting control method thereof

Abstract

The present application relates to a heat pump system, by setting the distance from the windward side fin to the coil is greater than the distance from the leeward side fin to the coil in the fin evaporator, and the sensor for obtaining the surface temperature of the windward side fin is placed in the windward side fin and does not contact the coil and is as far away from the coil as possible; and the defrosting control method designed based on this determines whether the heat pump system defrosts by obtaining the surface temperature of the windward side fin, the ambient temperature and the continuous cumulative running time of the compressor; also determines whether the heat pump system exits defrosting by obtaining the surface temperature of the windward side fin, the ambient temperature, or the defrosting time. The method makes the above-mentioned heat pump system in a low-temperature and high-humidity environment, can avoid the influence of the environmental temperature and the refrigerant temperature of the coil on the detected temperature parameter of the evaporator, and further cause the problem of inaccurate frost degree determination, at the same time, can improve the reliability and energy efficiency of defrosting.

Description

Technical Field

[0001] This invention relates to the field of heat pumps, and more particularly to a heat pump system and a defrosting control method thereof. Background Technology

[0002] Heat pump systems are highly efficient energy-saving devices. However, when operating in environments with extremely low outdoor temperatures and high relative humidity, their outdoor heat exchangers are particularly prone to frosting, sometimes to the point of becoming unusable. This leads to a continuous decrease in the heating efficiency of the heat pump system, reducing its overall energy efficiency. Therefore, it is necessary to set up defrost control to defrost the frosted outdoor heat exchanger.

[0003] Defrosting control involves determining the start and stop times of defrosting and implementing appropriate defrosting heat sources and procedures. The industry primarily uses "temperature-time" or "temperature difference-time" defrosting control methods. Temperature or temperature difference control uses factors such as the evaporator outlet air temperature, evaporator inlet air temperature, refrigerant temperature in the evaporator coils, the temperature difference between the evaporator outlet and inlet air temperatures, and the temperature difference between the refrigerant temperature in the evaporator coils and the temperature of the fins as criteria for starting or ending defrosting. Time control includes the compressor's running time and the defrosting program execution time as criteria for starting or ending defrosting. Both temperature and temperature difference controls determine the evaporation and frosting state by detecting the evaporator temperature and then determining defrosting control based on the compressor's running time.

[0004] Currently, heat pump systems mainly use the following methods to defrost the outdoor heat exchanger:

[0005] (1) Refrigerant reverse heat pump circulation defrosting: A four-way valve is installed in the refrigerant circulation pipeline. When defrosting, the four-way valve is switched so that the refrigerant absorbs heat from the hot water in the condenser and sends it to the outdoor heat exchanger to release heat and defrost.

[0006] (2) Bypass hot gas defrosting: A defrosting bypass is added to the compressor exhaust pipe, and a solenoid valve is installed on the defrosting bypass. When defrosting, the defrosting solenoid valve is opened to send the high-temperature and high-pressure refrigerant from the compressor exhaust port directly to the outdoor heat exchanger to release heat and defrost.

[0007] (3) Hot water spray defrosting: Install a defrosting solenoid valve on the hot water pipeline and directly use the hot water in the hot water storage tank to spray defrost the outdoor heat exchanger finned coils.

[0008] (4) Hot air defrosting: Install an electric heater at the front or rear of the outdoor heat exchanger and use the electric heater to generate hot air to blow air onto the finned coil of the outdoor heat exchanger for defrosting.

[0009] Regardless of the defrosting control method or defrosting method used, the goal should be thorough defrosting, energy saving, and simple control. However, the evaporator temperature parameter used as the basis for determining the start or end of defrosting is easily affected by the environment and the temperature of the refrigerant flowing through the evaporator coils. This can lead to inaccurate judgment of the frost state, resulting in deviations in defrosting time and causing incomplete defrosting or continuous defrosting even when there is no frost. Summary of the Invention

[0010] Based on this, the purpose of the present invention is to provide a heat pump system and its defrosting control method, which enables the heat pump system to avoid the problem of inaccurate determination of the degree of frost caused by the influence of the environment and the temperature of the coil refrigerant on the detected evaporator temperature parameters in low temperature and high humidity environments, thereby improving the energy efficiency and reliability of the defrosting mode.

[0011] A heat pump system includes a compressor, a four-way valve, a condenser, and a finned evaporator connected sequentially via refrigerant circulation piping; and a control device electrically and / or communicatively connected to the compressor and the four-way valve. The control device includes a temperature sensing component and a controller. The controller includes a first parameter acquisition module, a first judgment module, a first execution module, a second parameter acquisition module, a second judgment module, and a second execution module.

[0012] The first parameter acquisition module is used to acquire the first operating status parameters of the heat pump system when the heat pump system is in heating operation. The first operating status parameters include the continuous cumulative operating time of the compressor, the surface temperature of the finned evaporator on the windward side measured by the temperature measuring component, and the ambient temperature.

[0013] The first judgment module is used to compare and judge the first operating status parameters of the heat pump system with the first preset parameters, wherein the first preset parameters include a first preset temperature, a first preset temperature difference and a first preset running time.

[0014] The first execution module is used to send a frequency reduction command to the compressor, a valve switching command to the four-way valve, and an opening adjustment command to the expansion valve according to the judgment result output by the first judgment module, so that the heat pump system enters the defrosting working state.

[0015] The second parameter acquisition module is used to acquire the second operating status parameters of the heat pump system when the heat pump system is defrosting. The second operating status parameters include the defrosting time of the heat pump system, the surface temperature of the finned evaporator on the windward side measured by the temperature measuring component, and the ambient temperature.

[0016] The second judgment module is used to compare and judge the second operating status parameters of the heat pump system with the second preset parameters, wherein the second preset parameters include a second preset temperature difference and a second preset running time.

[0017] The second execution module is used to send a frequency reduction command to the compressor and a valve switching command to the four-way valve according to the judgment result output by the second judgment module, restore the PID control of the expansion valve opening, restore the automatic control of the compressor frequency, and enable the heat pump system to end defrosting.

[0018] Furthermore, the distance from the windward fins to the center of the coil in the finned evaporator is greater than the distance from the leeward fins to the center of the coil.

[0019] Furthermore, the temperature measuring component includes a first temperature sensor and a second temperature sensor; wherein, the first temperature sensor is disposed within the fins on the windward side of the finned evaporator and does not contact the coil and is as far away from the coil as possible, and is used to transmit the detected surface temperature signal of the windward side fins to the controller; the second temperature sensor is used to transmit the ambient temperature signal to the controller.

[0020] Furthermore, the first judgment module includes a first temperature judgment unit, a first temperature difference judgment unit, a first running time judgment unit, and a first judgment result output unit, wherein,

[0021] The first temperature determination unit is used to compare the acquired ambient temperature with a first preset temperature, and process the comparison result in the following manner:

[0022] If the ambient temperature is greater than or equal to the first preset temperature, return to the first parameter acquisition module;

[0023] If the ambient temperature is lower than the first preset temperature, then proceed to the first temperature difference judgment unit;

[0024] The first temperature difference judgment unit is used to calculate a first temperature difference between the ambient temperature and the surface temperature based on the acquired ambient temperature and the surface temperature of the fins on the windward side, compare the first temperature difference with a first preset temperature difference, and process the comparison result in the following manner:

[0025] If the first temperature difference is less than or equal to the first preset temperature difference, then return to the first parameter acquisition module;

[0026] If the first temperature difference is greater than the first preset temperature difference, then proceed to the first judgment result output unit;

[0027] The first running time determination unit is used to compare the acquired continuous running cumulative time with a first preset running time, and process the comparison result in the following manner:

[0028] If the cumulative continuous running time is less than or equal to the first preset running time, then return to the first parameter acquisition module;

[0029] If the cumulative continuous running time is greater than the first preset running time, then proceed to the first judgment result output unit;

[0030] The first judgment result output unit is used to output a judgment result signal to the first execution module based on the comparison result received from the first temperature difference judgment unit and the first running time judgment unit.

[0031] Furthermore, the second judgment module includes a second temperature difference judgment unit and a second running time judgment unit, wherein,

[0032] The second temperature difference judgment unit is used to calculate a second temperature difference between the ambient temperature and the surface temperature based on the acquired ambient temperature and the surface temperature of the windward fins, compare the second temperature difference with a second preset temperature difference, and process the comparison result in the following manner:

[0033] If the second temperature difference is greater than or equal to the second preset temperature difference, then return to the second parameter acquisition module;

[0034] If the second temperature difference is less than the second preset temperature difference, then proceed to the second execution module;

[0035] The second running time determination unit is used to compare the obtained defrosting time of the heat pump system with the second preset running time, and process the comparison result in the following manner:

[0036] If the defrosting time is less than the second preset running time, return to the second parameter acquisition module;

[0037] If the defrosting time is greater than or equal to the second preset running time, then proceed to the second execution module.

[0038] Compared with existing technologies, the heat pump system of this invention improves the relative positional relationship between the coil and the windward and leeward fins in the finned evaporator. This ensures the distance from the windward fins to the coil is greater than the distance from the leeward fins to the coil. Furthermore, the sensor for acquiring the surface temperature of the windward fins is placed within the windward fins, away from the coil, effectively preventing the acquired surface temperature from being affected by the refrigerant temperature flowing through the coil and the ambient temperature. Based on this, the designed defrosting control method determines whether the heat pump system needs to defrost by acquiring the surface temperature of the windward fins, the ambient temperature, and the compressor's continuous cumulative operating time; it also determines whether the heat pump system has exited defrosting by acquiring the surface temperature of the windward fins, the ambient temperature, or the defrosting time. This method enables the aforementioned heat pump system to avoid inaccurate frost level determination caused by the influence of ambient temperature and coil refrigerant temperature on the detected evaporator temperature parameters in low-temperature, high-humidity environments. Simultaneously, it improves the reliability and energy efficiency of defrosting.

[0039] The present invention proposes a defrosting control method for a heat pump system, comprising the following control steps:

[0040] S10 When the heat pump system is in heating operation, the first operating status parameters of the heat pump system are obtained. The first operating status parameters include the continuous running time of the compressor, the surface temperature of the finned evaporator on the windward side measured by the temperature measuring component, and the ambient temperature.

[0041] S20 makes a judgment by comparing the first operating status parameters of the heat pump system with the first preset parameters, wherein the first preset parameters include the first preset temperature, the first preset temperature difference and the first preset operating time.

[0042] S30 Based on the judgment result output in step S20, a frequency reduction command is sent to the compressor, a valve switching command is sent to the four-way valve, and an opening adjustment command is sent to the expansion valve, so that the heat pump system enters the defrosting working state.

[0043] S40 When the heat pump system is defrosting, it acquires the second operating status parameters of the heat pump system. The second operating status parameters include the defrosting time of the heat pump system, the surface temperature of the finned evaporator on the windward side measured by the temperature measuring component, and the ambient temperature.

[0044] S50 makes a judgment by comparing the second operating status parameters of the heat pump system with the second preset parameters, wherein the second preset parameters include the second preset temperature difference and the second preset operating time;

[0045] Based on the judgment result output in step S50, S60 sends a frequency reduction command to the compressor and a valve switching command to the four-way valve, restores the PID control of the expansion valve opening, restores the automatic control of the compressor frequency, and ends the defrosting process of the heat pump system.

[0046] The details of this defrosting control method and its resulting technical effects are similar to those of the heat pump system described above, and will not be repeated here.

[0047] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of a heat pump system under defrosting control according to an embodiment of the present invention;

[0049] Figure 2 This is a side view of a finned evaporator according to an embodiment of the present invention;

[0050] Figure 3 This is a cross-sectional view of the structure of a finned evaporator according to an embodiment of the present invention;

[0051] Figure 4 for Figure 3 A schematic diagram showing the location of the temperature sensor;

[0052] Figure 5 This is a flowchart of a defrosting control method for a heat pump system according to an embodiment of the present invention. Detailed Implementation

[0053] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings of the embodiments of the present invention.

[0054] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that, unless otherwise stated, “a plurality” means two or more; and the term “and / or” as used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0055] In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. In the description of this application, it should be understood that the terms "first," "second," "third," etc., are used only for distinction and not to describe a specific order or sequence, nor should they be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0056] To address the issue that the evaporator temperature measurement parameter, used as the basis for determining the start or end of defrosting in the "temperature-time" defrosting control method for outdoor heat exchangers in heat pump systems, is easily affected by the environment and the temperature of the refrigerant flowing through the evaporator coils. This leads to inaccurate judgment of the frosting state, resulting in deviations in defrosting time and causing incomplete defrosting or continuous defrosting even when there is no frost. The inventors carefully studied the relationship between the surface temperature of the evaporator fins and frosting / defrosting. Under relatively low ambient temperature and high humidity conditions, after the compressor has been running continuously for a period of time, frost will begin to appear on the windward side of the evaporator fins, and the surface temperature of the windward side of the evaporator fins will begin to decrease. As the compressor continues to run, the frosted area on the evaporator fins becomes larger and the frost layer becomes thicker, causing a continuous reduction in the air intake of the evaporator, further aggravating the frosting. At this time, the evaporator coils also begin to frost, and the surface temperature of the evaporator fins further decreases as the frosting intensifies. During defrosting, the frost layer on the outside of the evaporator coil melts first, at which point the temperature of the evaporator fin surface remains low. During continuous defrosting, defrosting the evaporator fins is difficult and the defrosting time is hard to control. However, the evaporator fin surface temperature gradually rises during defrosting until defrosting is complete, at which point the evaporator fin surface temperature is relatively close to the ambient temperature. Based on this, after research and debugging, this invention designs a heat pump system. This system uses an improved finned heat exchanger to obtain a fin surface temperature unaffected by the environment and coil. Based on the obtained fin surface temperature, a defrosting control method is designed. When applied to the aforementioned heat pump system, this control method effectively solves the technical problems existing in the "temperature-time" defrosting control method used for the outdoor heat exchanger in the above-mentioned heat pump system.

[0057] For specific implementation details, please refer to [link / reference]. Figure 1The heat pump system proposed in this invention includes a compressor 10, a four-way valve 20, a finned tube evaporator 30, an expansion valve 40, a condenser 50, a control device (not shown), and other auxiliary pipes. The compressor 10, four-way valve 20, finned tube evaporator 30, expansion valve 40, and condenser 50 are sequentially connected via refrigerant piping. The control device is electrically or communicatively connected to the compressor 10, four-way valve 20, and expansion valve 40. Specifically, the exhaust port A of the compressor 10, the inlet port D of the four-way valve 20, the first working port E of the four-way valve 20, the finned tube evaporator 30, expansion valve 40, condenser 50, the second working port C of the four-way valve 20, and the return port S of the four-way valve 20 are sequentially connected to the return port B of the compressor 10 to form a refrigerant circulation pipeline. When the heat pump system defrosts, the high-temperature and high-pressure gaseous refrigerant generated by the compressor flows through the finned tube evaporator 30, releasing heat to the finned tube evaporator 30 to heat and defrost the frost on its outer surface.

[0058] Please see Figure 2 The finned tube evaporator 30 includes windward-facing fins 31, leeward-facing fins 32, and a coil 33. The distance 'a' from the center of the windward-facing fins 31 to the center of the coil 33 is greater than the distance 'b' from the center of the leeward-facing fins 32 to the center of the coil 33. A sensor housing space W is provided on the windward-facing fins 31 facing the coil 33; this housing space W does not contact the coil 33 and is as far away from the coil 33 as possible.

[0059] The control device includes a temperature measuring component (not shown) and a controller (not shown). The temperature measuring component, compressor 10, four-way valve 20, and expansion valve 40 are electrically or communicatively connected to the controller. The temperature measuring component includes a first temperature sensor (not shown) and a second temperature sensor (not shown). The first temperature sensor is disposed in the accommodating space of the windward fin 31 and transmits the detected temperature signal of the windward fin 31 to the controller. The second temperature sensor transmits the ambient temperature signal to the controller. The controller receives the measurement signal from the temperature measuring component and the cumulative continuous operating time signal of the compressor 10. It then sends defrost start or defrost end signals to the compressor 10 and four-way valve 20 via a defrost control program stored on the controller, controlling the start and stop of the compressor 10 and the valve switching of the four-way valve 20. Furthermore, it sends an opening adjustment signal to the expansion valve 40 via an expansion valve opening control program stored on the controller, controlling the refrigerant flow rate.

[0060] The controller is further configured with a first parameter acquisition module 100, a first judgment module 200, a first execution module 300, a second parameter acquisition module 400, a second judgment module 500, and a second execution module 600. The controller controls the defrosting operation of the heat pump system through the following steps.

[0061] S10 First parameter acquisition module 100 is used to acquire first operating status parameters of the heat pump system when the heat pump system is in heating operation. The first operating status parameters include the cumulative continuous operating time of the compressor 10. The surface temperature of the windward fin 31 measured by the first temperature sensor. The ambient temperature measured by the second temperature sensor .

[0062] S20 The first judgment module 200 is used to compare and judge the first operating status parameters of the heat pump system obtained with the first preset parameters set by the program, wherein the first preset parameters include a first preset temperature. First preset temperature difference and the first preset runtime .

[0063] In specific implementation, the first judgment module 200 includes a first temperature judgment unit 210, a first temperature difference judgment unit 220, a first running time judgment unit 230, and a first judgment result output unit 240.

[0064] S21 The first temperature judgment unit 210 is used to determine the acquired ambient temperature. With the first preset temperature Comparison:

[0065] If the ambient temperature Greater than or equal to the first preset temperature Then return to step S10;

[0066] If the ambient temperature Less than the first preset temperature Then proceed to step S22.

[0067] Specifically, the first preset temperature The settings can be adjusted based on the environment in which the heat pump system is located, taking into account both ambient temperature and humidity. The recommended range is [5℃, 20℃].

[0068] S22 The first temperature difference judgment unit 220 is used to determine the ambient temperature based on the acquired ambient temperature. Surface temperature of the windward side fin 31 Calculate ambient temperature With surface temperature First temperature difference and the first temperature difference With the first preset temperature difference Comparison:

[0069] If the first temperature difference Less than or equal to the first preset temperature difference Then return to step S10;

[0070] If the first temperature difference Greater than the first preset temperature difference Then proceed to step S24.

[0071] Specifically, the first preset temperature difference The settings can be adjusted based on the environment in which the heat pump system is located, taking into account both ambient temperature and humidity. The recommended range is [0℃, 20℃].

[0072] S23 The first running time determination unit 230 is used to determine the acquired continuous running cumulative time. With the first preset running time Comparison:

[0073] If the cumulative time of continuous operation Less than or equal to the first preset running time Then return to step S10;

[0074] If the cumulative time of continuous operation Greater than the first preset running time Then proceed to step S24.

[0075] Specifically, the first preset runtime The settings can be determined based on the environment in which the heat pump system is located, taking into account the ambient temperature, humidity and compressor operating frequency. The recommended range is [10min, 120min].

[0076] S24 First Judgment Result Output Unit 240, used to output the first judgment result based on the received comparison result of steps S22 and S23, i.e., the first temperature difference. Greater than the first preset temperature difference And the cumulative time of continuous operation Greater than the first preset running time The judgment result signal is output to the first execution module 300.

[0077] S30 First execution module 300 is used to send a frequency reduction command to compressor 10, a valve switching command to four-way valve 20, and an opening adjustment command to expansion valve 40 according to the judgment result output by the first judgment module, so that the heat pump system enters the defrosting working state.

[0078] S40 Second parameter acquisition module 400 is used to acquire a second operating status parameter of the heat pump system when the heat pump system is defrosting, the second operating status parameter including the defrosting time of the heat pump system. The surface temperature of the windward fin 31 measured by the first temperature sensor. The ambient temperature measured by the second temperature sensor .

[0079] S50 The second judgment module 500 is used to compare and judge the second operating status parameters of the heat pump system obtained with the second preset parameters set by the program, wherein the second preset parameters include a second preset temperature difference. Second preset running time .

[0080] In specific implementation, the second judgment module 500 includes a second temperature difference judgment unit 510 and a second running time judgment unit 520.

[0081] S51 The second temperature difference judgment unit 510 is used to determine the ambient temperature based on the acquired ambient temperature. Surface temperature of the windward side fin 31 Calculate ambient temperature With surface temperature The second temperature difference and the second temperature difference With the second preset temperature difference Comparison:

[0082] If the second temperature difference Greater than or equal to the second preset temperature difference Then return to step S40;

[0083] If the second temperature difference Less than the second preset temperature difference Then proceed to step S60.

[0084] Specifically, the second preset temperature difference The settings can be adjusted based on the environment in which the heat pump system is located, taking into account both ambient temperature and humidity. The recommended range is [-50℃, 0℃].

[0085] S52 The second running time determination unit 230 is used to determine the obtained defrosting time of the heat pump system. With the second preset running time Comparison:

[0086] If defrosting time Less than the second preset running time Then return to step S40;

[0087] If defrosting time Greater than or equal to the second preset running time Then proceed to step S60.

[0088] Specifically, the second preset runtime The settings can be adjusted based on the environment in which the heat pump system is located, taking into account ambient temperature and humidity. The recommended range is [3 min, 20 min].

[0089] S60 Second execution module 600 is used to send a frequency reduction command to compressor 10 and a valve switching command to four-way valve 20 according to the judgment result output by the second judgment module, restore the PID control of the opening degree of expansion valve 40, restore the automatic frequency control of compressor 10, and end the defrosting of heat pump system.

[0090] The heat pump system of this invention improves the relative positional relationship between the coil and the windward and leeward fins in the finned evaporator, ensuring that the distance from the windward fins to the coil is greater than the distance from the leeward fins to the coil. Furthermore, the sensor for acquiring the surface temperature of the windward fins is placed within the windward fins, away from the coil and as far away from it as possible. This effectively avoids the influence of the refrigerant temperature flowing through the coil and the ambient temperature on the acquired surface temperature of the windward fins. Based on this, the designed defrosting control method determines whether the heat pump system needs to defrost by acquiring the surface temperature of the windward fins, the ambient temperature, and the continuous cumulative running time of the compressor; it also determines whether the heat pump system has exited defrosting by acquiring the surface temperature of the windward fins, the ambient temperature, or the defrosting time. This method enables the aforementioned heat pump system to avoid the problem of inaccurate frost determination caused by the influence of ambient temperature and coil refrigerant temperature on the detected evaporator temperature parameters in low-temperature, high-humidity environments. Simultaneously, it improves the reliability and energy efficiency of defrosting.

[0091] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and the present invention also intends to include these modifications and variations.

Claims

1. A heat pump system, comprising a compressor, a four-way valve, a finned evaporator, an expansion valve, and a condenser connected sequentially via a refrigerant circulation pipeline, and a control device electrically and / or communicatively connected to the compressor, the four-way valve, and the expansion valve, wherein the control device includes a temperature sensing component and a controller, characterized in that, The temperature measurement component includes a first temperature sensor and a second temperature sensor; wherein, the first temperature sensor is disposed within the fins on the windward side of the finned evaporator, not in contact with the coil and as far away from the coil as possible, and is used to transmit the detected surface temperature signal of the windward side fins to the controller; the second temperature sensor is used to transmit the ambient temperature signal to the controller; the controller includes a first parameter acquisition module, a first judgment module, a first execution module, a second parameter acquisition module, a second judgment module, and a second execution module; wherein... The first parameter acquisition module is used to acquire the first operating status parameters of the heat pump system when the heat pump system is in heating operation. The first operating status parameters include the continuous cumulative operating time of the compressor, the surface temperature of the finned evaporator on the windward side measured by the temperature measuring component, and the ambient temperature. The first judgment module is used to compare and judge the first operating status parameters of the heat pump system with the first preset parameters, wherein the first preset parameters include a first preset temperature, a first preset temperature difference, and a first preset operating time. When the ambient temperature is lower than the first preset temperature, and the first temperature difference between the ambient temperature and the surface temperature is greater than the first preset temperature difference, and the cumulative continuous operation time is greater than the first preset operating time, the heat pump system is determined to meet the defrosting conditions and enters the first execution module. The first execution module is used to send a frequency reduction command to the compressor, a valve switching command to the four-way valve, and an opening adjustment command to the expansion valve according to the judgment result output by the first judgment module, so that the heat pump system enters the defrosting working state. The second parameter acquisition module is used to acquire the second operating status parameters of the heat pump system when the heat pump system is defrosting. The second operating status parameters include the defrosting time of the heat pump system, the surface temperature of the finned evaporator on the windward side measured by the temperature measuring component, and the ambient temperature. The second judgment module is used to compare and judge the second operating status parameters of the heat pump system with the second preset parameters, wherein the second preset parameters include a second preset temperature difference and a second preset running time. The second execution module is used to send a frequency reduction command to the compressor and a valve switching command to the four-way valve according to the judgment result output by the second judgment module, restore the PID control of the expansion valve opening, restore the automatic control of the compressor frequency, and enable the heat pump system to end defrosting.

2. The heat pump system according to claim 1, characterized in that, The distance from the windward fins to the center of the coil in the finned evaporator is greater than the distance from the leeward fins to the center of the coil.

3. The heat pump system according to any one of claims 1 and 2, characterized in that, The first judgment module includes a first temperature judgment unit, a first temperature difference judgment unit, a first running time judgment unit, and a first judgment result output unit, wherein, The first temperature determination unit is used to compare the acquired ambient temperature with a first preset temperature, and process the comparison result in the following manner: If the ambient temperature is greater than or equal to the first preset temperature, return to the first parameter acquisition module; If the ambient temperature is lower than the first preset temperature, then proceed to the first temperature difference judgment unit; The first temperature difference judgment unit is used to calculate a first temperature difference between the ambient temperature and the surface temperature based on the acquired ambient temperature and the surface temperature of the fins on the windward side, compare the first temperature difference with a first preset temperature difference, and process the comparison result in the following manner: If the first temperature difference is less than or equal to the first preset temperature difference, then return to the first parameter acquisition module; If the first temperature difference is greater than the first preset temperature difference, then proceed to the first judgment result output unit; The first running time determination unit is used to compare the acquired continuous running cumulative time with a first preset running time, and process the comparison result in the following manner: If the cumulative continuous running time is less than or equal to the first preset running time, then return to the first parameter acquisition module; If the cumulative continuous running time is greater than the first preset running time, then proceed to the first judgment result output unit; The first judgment result output unit is used to output a judgment result signal to the first execution module based on the comparison result received from the first temperature difference judgment unit and the first running time judgment unit.

4. The heat pump system according to claim 3, characterized in that, The second judgment module includes a second temperature difference judgment unit and a second running time judgment unit, wherein, The second temperature difference judgment unit is used to calculate a second temperature difference between the ambient temperature and the surface temperature based on the acquired ambient temperature and the surface temperature of the windward fins, compare the second temperature difference with a second preset temperature difference, and process the comparison result in the following manner: If the second temperature difference is greater than or equal to the second preset temperature difference, then return to the second parameter acquisition module; If the second temperature difference is less than the second preset temperature difference, then proceed to the second execution module; The second running time determination unit is used to compare the obtained defrosting time of the heat pump system with the second preset running time, and process the comparison result in the following manner: If the defrosting time is less than the second preset running time, return to the second parameter acquisition module; If the defrosting time is greater than or equal to the second preset running time, then proceed to the second execution module.

5. The heat pump system according to claim 1, characterized in that, The first preset temperature range is [5℃, 20℃], the first preset temperature difference range is [0℃, 20℃], the second preset temperature difference range is [-50℃, 0℃], and the second preset running time range is [3min, 20min].

6. A defrosting control method for a heat pump system, the heat pump system comprising a compressor, a four-way valve, a condenser, and a finned evaporator connected sequentially via a refrigerant circulation pipeline, and a control device electrically and / or communicatively connected to the compressor and the four-way valve, the control device comprising a temperature measuring component and a controller, characterized in that, The temperature measuring component includes a first temperature sensor and a second temperature sensor; wherein, the first temperature sensor is disposed within the fins on the windward side of the finned evaporator and does not contact the coil and is as far away from the coil as possible, for transmitting the detected surface temperature signal of the windward side fins to the controller; the second temperature sensor is used to transmit the ambient temperature signal to the controller; the defrosting control method of the heat pump system includes the following steps: S10 When the heat pump system is in heating operation, the first operating status parameters of the heat pump system are obtained. The first operating status parameters include the continuous running time of the compressor, the surface temperature of the finned evaporator on the windward side measured by the temperature measuring component, and the ambient temperature. S20 determines the operation status based on the first operating state parameters of the heat pump system compared with the first preset parameters, wherein the first preset parameters include a first preset temperature, a first preset temperature difference, and a first preset operating time. When the ambient temperature is lower than the first preset temperature, and the first temperature difference between the ambient temperature and the surface temperature is greater than the first preset temperature difference, and the cumulative continuous operation time is greater than the first preset operating time, it is determined that the heat pump system meets the defrosting conditions, and step S30 is executed. S30 Based on the judgment result output in step S20, a frequency reduction command is sent to the compressor, a valve switching command is sent to the four-way valve, and an opening adjustment command is sent to the expansion valve, so that the heat pump system enters the defrosting working state. S40 When the heat pump system is defrosting, it acquires the second operating status parameters of the heat pump system. The second operating status parameters include the defrosting time of the heat pump system, the surface temperature of the finned evaporator on the windward side measured by the temperature measuring component, and the ambient temperature. S50 makes a judgment by comparing the second operating status parameters of the heat pump system with the second preset parameters, wherein the second preset parameters include the second preset temperature difference and the second preset operating time; Based on the judgment result output in step S50, S60 sends a frequency reduction command to the compressor and a valve switching command to the four-way valve, restores the PID control of the expansion valve opening, restores the automatic control of the compressor frequency, and ends the defrosting process of the heat pump system.

7. The defrosting control method according to claim 6, characterized in that, Step S20 includes the following sub-steps: S21 compares the acquired ambient temperature with the first preset temperature: If the ambient temperature is greater than or equal to the first preset temperature, return to step S10; If the ambient temperature is lower than the first preset temperature, then proceed to step S22; S22 calculates the first temperature difference between the ambient temperature and the surface temperature based on the obtained ambient temperature and the surface temperature of the fins on the windward side, and compares the first temperature difference with a first preset temperature difference: If the first temperature difference is less than or equal to the first preset temperature difference, then return to step S10; If the first temperature difference is greater than the first preset temperature difference, then proceed to step S24; S23 compares the acquired continuous running time with the first preset running time: If the cumulative continuous running time is less than or equal to the first preset running time, then return to step S10; If the cumulative continuous running time is greater than the first preset running time, then proceed to step S24; S24 Based on the comparison results received from the first temperature difference judgment unit and the first running time judgment unit, output the judgment result signal to the first execution module.

8. The defrosting control method according to any one of claims 6 or 7, characterized in that, Step S50 includes the following sub-steps: S51 calculates a second temperature difference between the ambient temperature and the surface temperature based on the obtained ambient temperature and the surface temperature of the windward side fins, and compares the second temperature difference with a second preset temperature difference: If the second temperature difference is greater than or equal to the second preset temperature difference, then return to step S40; If the second temperature difference is less than the second preset temperature difference, then proceed to step S60; S52 compares the obtained defrosting time of the heat pump system with the second preset running time, and processes the comparison result as follows: If the defrosting time is less than the second preset running time, return to step S40; If the defrosting time is greater than or equal to the second preset running time, then proceed to step S60.

9. The defrosting control method according to claim 6, characterized in that, The first preset temperature range is [5℃, 20℃], the first preset temperature difference range is [0℃, 20℃], the second preset temperature difference range is [-50℃, 0℃], and the second preset running time range is [3min, 20min].

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